1. Field of the Invention
The present invention relates to a liquid drain trap device to be used for any liquid drain piping in any biochemical analysis or other chemical analysis processing system, particularly a trap device which can be advantageously used to separate a liquid from a vacuum-sucked air therein in a piping system for drainage of a liquid such as cleaning solution, for example, used for a B/F (bound/free) separation for immunological analysis.
2. Description of the Related Art
In the biochemical analysis or any other type of chemical analysis, solutions such as reagents in reaction vessels have been conventionally removed by cleaning the vessels.
Such a cleaning equipment of conventional type comprises a piping system for supplying a cleaning solution and a piping system for draining the cleaning solution. Especially, the piping system for drainage of cleaning solution conventionally comprises a trap unit as well as a solenoid valve for controlling the opening and closing of a cleaning solution drain piping, which are installed between a vacuum source such as vacuum (pressure reducing) system and the cleaning solution drain piping equipped with a nozzle pipe connected to a reaction or other vessel filled with a liquid to be drained, so as to drain the cleaning solution away from the reaction or other vessel through the trap unit by using the air suction provided by the vacuum source.
The vacuum source comprises a combination of a vacuum pump and a vacuum tank in general.
The trap unit of conventional type comprises a vertically-elongated hollow container for storing a cleaning solution to be drained and an air suction pipe connected between the top of the container and the above-described vacuum source so as to suck up the cleaning solution in the container and store it in the bottom part of the container by receiving a negative pressure (air suction pressure) supplied by the vacuum source, and to drain the cleaning solution off the bottom part of the vessel by means of a three-way valve when an adequate quantity of cleaning solution is stored in the bottom part of the container. More specifically the cleaning solution is drained by changing over the three-way valve so as to restore the pressure in the container to the atmospheric pressure and then opening the valve located at the lower portion of the container.
During the continuous operation, however, the above-described trap unit presents disadvantages as follows:
The above-described trap unit is designed so that it sucks up the cleaning solution by the air suction or negative-pressure action provided by the vacuum source. Therefore, the cleaning solution and air jet dashingly into the container of the trap unit through the nozzle pipe connected to the reaction or other vessel to inevitably form bubbles in the cleaning solution stored in the container with high possibility.
If such bubbles are produced, a liquid film is formed and grows in the interior of the container, and it is sucked gradually upward in the container under the air suction by the vacuum source until the liquid may enter into the vacuum source system through an air suction pipe. The liquid sucked in the vacuum source system may cause a detriment such as failure of the vacuum pump or other unit. Therefore, it is necessary to drain the liquid off in time by using any applicable means.
The conventional type of vacuum source system generally comprises a drain pipe connected to the vacuum tank and equipped with a drain valve to drain the vacuum tank of the cleaning solution stored therein by means of the drain valve in time, so as to prevent the cleaning solution from entering the vacuum pump as vacuum source.
However, the vacuum system which requires to drain the vacuum tank of the cleaning solution presents the inconvenience that the interior of the vacuum tank returns under the atmospheric pressure each time when the tank is drained, which requires an onerous operation to recover the predetermined negative pressure in the interior of the tank when the vacuum system is restarted, and a waiting time while the vacuum condition is created just after the restart of the vacuum system.
To reduce this inconvenience, it is possible to take measures such as increasing the capacity of the container in the trap unit to decrease the draining operations for the vacuum tank. However, this solution cannot eliminate the inconvenience that it takes a long time to recover the predetermined negative pressure in the interior of the tank after the restart of the system.